Your boiler has detected a problem with one of its internal temperature sensors, which means it cannot safely monitor how hot the water or exhaust gases are getting.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Temperature sensors faulty (CH sensor or Flue sensor).
What causes this fault?
This fault occurs when the boiler's control board loses communication with its temperature sensors or receives a reading that is outside of the safe range. The most common reason is that the internal thermistor has chemically degraded over time, or the electrical wiring connecting the sensor has become loose or damaged due to heat exposure.
This fault is slightly more common in autumn and winter when the boiler is pushed to operate at higher temperatures for longer periods, placing more thermal stress on aging sensors.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E06 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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